Direct Electrodeposition of Carbon Dots Modifying Bismuth Film Electrode for Sensitive Detection of Cd2+ and Pb2+

A sensitive, selective, and stable sensor for the simultaneous determination of Cd2+ and Pb2+ in aqueous solution has been developed based on the carbon dots (CDs) and Nafion-modified bismuth film glassy carbon electrode (GCE). High graphitized CDs prepared by the sulfuric acid-assisted hydrothermal synthesis were directly electrodeposited on the GCE surface by cyclic voltammetry. Compared with the conventional bismuth film electrodes, CDs greatly improved the electrochemical activity of the bismuth film electrode for the detection of Cd2+ and Pb2+. After decorating CDs, the surface impedance of the GCE was decreased from 10.9 kΩ to 4.84 kΩ. Meanwhile, the corresponding response currents of the Bi/GCE were increased over 7.4 and 2.4 times for Cd2+ and Pb2+ with a wide linear range of 0.05-0.50 mg/L, respectively. High sensitivity was obtained with the detection limits of 3.1 μg L-1 (Cd2+) and 2.3 μg L-1 (Pb2+). Moreover, good stability was obtained for the simultaneous determination of Cd2+ and Pb2+ in the practical underground water with the relative standard deviations less than 10%. The results indicated that the CDs-modified bismuth film electrode could potentially be applied to detect the heavy metal ion concentrations in practical environment.

Voltammetry Determination of Pb(II), Cd(II), and Zn(II) at Bismuth Film Electrode Combined with 8-Hydroxyquinoline as a Complexing Agent

A novel method was developed for the simultaneous determination of Pb(II), Cd(II), and Zn(II) based on the cathodic stripping response at a bismuth film electrode associated with oxine as a chelating agent. The developed method provided a high and sharp electrochemical response compared with the method without oxine. A linear response of peak currents was observed for Pb(II), Cd(II), and Zn(II) concentration in the range from 2 ppb to 110 ppb. The detection limits of Pb(II), Cd(II), and Zn(II) were 0.45, 0.17, and 0.78 ppb, respectively. This method was successfully applied to the determination of Pb(II), Cd(II), and Zn(II) in lake-water and river-water samples. The metals were detected at the ultratrace level, showing the feasibility of the proposed method for environmental applications.

Nanostructured Bismuth Film Electrode for Detection of Progesterone

Progesterone is an important hormone responsible, among others, for maintaining pregnancy via inhibition of uterus muscles activity; thus, following its concentration levels in pregnant women is of immense importance in the endeavor to prevent premature birth. In this work, the nanostructured bismuth film electrode (nsBiFE) was studied for detection of progesterone in neutral medium. Due to the ability to accumulate progesterone at the nsBiFE, the adsorptive cathodic stripping voltammetry was beneficially exploited. The nsBiFE was prepared on the surface of a glassy carbon supporting electrode and several parameters influencing the detection of progesterone were investigated. The nsBiFE exhibited superior electroanalytical characteristics in comparison to other bismuth-based electrodes and unmodified glassy carbon electrode together with satisfactory response toward low concentrations of progesterone, which are consistent with clinically significant levels

Inexpensive Bismuth-Film Electrode Supported on Pencil-Lead Graphite for Determination of Pb(II) and Cd(II) Ions by Anodic Stripping Voltammetry

The present work reports the development and application of bismuth-film electrode (BiFE), obtained by in situ method on the pencil-lead graphite surface, for simultaneous Cd(II) and Pb(II) determination at trace levels, as alternative to replace the mercury-film electrodes. Experimental factors, deposition time (td), deposition potential (Ed), and Bi(III) concentration (CBi), were investigated by applying a 23 factorial design using 0.10 mol/L acetate buffer solution (pH 4.5) as supporting electrolyte. The analysis conditions of the differential pulse technique were td = 250 s, Ed = -1.40 V, and CBi = 250 mg L−1. The validation of the method employing BiFE was accomplished by determination of merit figures. The detection limits were of 11.0 μg L−1 for Cd(II) and 11.5 μg L−1 for Pb(II), confirming that proposed method is attractive and suitable for heavy metals determination. Additionally, the BiFE developed was successfully applied for the Cd(II) and Pb(II) determination in wastewater sample of battery industry.